HHH-17355 Add array_trim function

documentation/src/main/asciidoc/userguide/chapters/query/hql/QueryLanguage.adoc

@@ -1134,6 +1134,7 @@ The following functions deal with SQL array types, which are not supported on ev
 | `array_remove_index()` | Creates array copy with the element at the given index removed
 | `array_slice()` | Creates a sub-array of the based on lower and upper index
 | `array_replace()` | Creates array copy replacing a given element with another
+| `array_trim()` | Creates array copy trimming the last _N_ elements
 |===
 
 ===== `array()`
@@ -1385,6 +1386,19 @@ include::{array-example-dir-hql}/ArrayReplaceTest.java[tags=hql-array-replace-ex
 ----
 ====
 
+===== `array_trim()`
+
+Returns an array copy without the last _N_ elements, specified by the second argument.
+It is an error if any array has a length smaller than the second argument.
+
+[[hql-array-trim-example]]
+====
+[source, JAVA, indent=0]
+----
+include::{array-example-dir-hql}/ArrayTrimTest.java[tags=hql-array-trim-example]
+----
+====
+
 [[hql-user-defined-functions]]
 ==== Native and user-defined functions
 

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/CockroachLegacyDialect.java

@@ -476,6 +476,7 @@ public class CockroachLegacyDialect extends Dialect {
 		functionFactory.arrayRemoveIndex_unnest( true );
 		functionFactory.arraySlice_operator();
 		functionFactory.arrayReplace();
+		functionFactory.arrayTrim_trim_array();
 
 		functionContributions.getFunctionRegistry().register(
 				"trunc",

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/H2LegacyDialect.java

@@ -384,6 +384,7 @@ public class H2LegacyDialect extends Dialect {
 				functionFactory.arrayRemoveIndex_h2( getMaximumArraySize() );
 				functionFactory.arraySlice();
 				functionFactory.arrayReplace_h2( getMaximumArraySize() );
+				functionFactory.arrayTrim_trim_array();
 			}
 			else {
 				// Use group_concat until 2.x as listagg was buggy

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/HSQLLegacyDialect.java

@@ -262,6 +262,7 @@ public class HSQLLegacyDialect extends Dialect {
 		functionFactory.arrayRemoveIndex_unnest( false );
 		functionFactory.arraySlice_unnest();
 		functionFactory.arrayReplace_unnest();
+		functionFactory.arrayTrim_trim_array();
 	}
 
 	@Override

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/OracleLegacyDialect.java

@@ -298,6 +298,7 @@ public class OracleLegacyDialect extends Dialect {
 		functionFactory.arrayRemoveIndex_oracle();
 		functionFactory.arraySlice_oracle();
 		functionFactory.arrayReplace_oracle();
+		functionFactory.arrayTrim_oracle();
 	}
 
 	@Override

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/PostgreSQLLegacyDialect.java

@@ -596,6 +596,7 @@ public class PostgreSQLLegacyDialect extends Dialect {
 		functionFactory.arrayRemoveIndex_unnest( true );
 		functionFactory.arraySlice_operator();
 		functionFactory.arrayReplace();
+		functionFactory.arrayTrim_trim_array();
 
 		if ( getVersion().isSameOrAfter( 9, 4 ) ) {
 			functionFactory.makeDateTimeTimestamp();

hibernate-core/src/main/java/org/hibernate/dialect/CockroachDialect.java

@@ -463,6 +463,7 @@ public class CockroachDialect extends Dialect {
 		functionFactory.arrayRemoveIndex_unnest( true );
 		functionFactory.arraySlice_operator();
 		functionFactory.arrayReplace();
+		functionFactory.arrayTrim_trim_array();
 
 		functionContributions.getFunctionRegistry().register(
 				"trunc",

hibernate-core/src/main/java/org/hibernate/dialect/H2Dialect.java

@@ -323,6 +323,7 @@ public class H2Dialect extends Dialect {
 		functionFactory.arrayRemoveIndex_h2( getMaximumArraySize() );
 		functionFactory.arraySlice();
 		functionFactory.arrayReplace_h2( getMaximumArraySize() );
+		functionFactory.arrayTrim_trim_array();
 	}
 
 	/**

hibernate-core/src/main/java/org/hibernate/dialect/HSQLDialect.java

@@ -202,6 +202,7 @@ public class HSQLDialect extends Dialect {
 		functionFactory.arrayRemoveIndex_unnest( false );
 		functionFactory.arraySlice_unnest();
 		functionFactory.arrayReplace_unnest();
+		functionFactory.arrayTrim_trim_array();
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/dialect/OracleArrayJdbcType.java

@@ -471,6 +471,28 @@ public class OracleArrayJdbcType extends ArrayJdbcType {
 						false
 				)
 		);
+		database.addAuxiliaryDatabaseObject(
+				new NamedAuxiliaryDatabaseObject(
+						arrayTypeName + "_trim",
+						database.getDefaultNamespace(),
+						new String[]{
+								"create or replace function " + arrayTypeName + "_trim(arr in " + arrayTypeName +
+										", elems number) return " + arrayTypeName + " deterministic is " +
+										"res " + arrayTypeName + ":=" + arrayTypeName + "(); begin " +
+										"if arr is null or elems is null then return null; end if; " +
+										"if arr.count < elems then raise_application_error (-20000, 'number of elements to trim must be between 0 and '||arr.count); end if;" +
+										"for i in 1 .. arr.count-elems loop " +
+										"res.extend; " +
+										"res(i) := arr(i); " +
+										"end loop; " +
+										"return res; " +
+										"end;"
+						},
+						new String[] { "drop function " + arrayTypeName + "_trim" },
+						emptySet(),
+						false
+				)
+		);
 	}
 
 	protected String createOrReplaceConcatFunction(String arrayTypeName) {

hibernate-core/src/main/java/org/hibernate/dialect/OracleDialect.java

@@ -327,6 +327,7 @@ public class OracleDialect extends Dialect {
 		functionFactory.arrayRemoveIndex_oracle();
 		functionFactory.arraySlice_oracle();
 		functionFactory.arrayReplace_oracle();
+		functionFactory.arrayTrim_oracle();
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/dialect/PostgreSQLDialect.java

@@ -644,6 +644,7 @@ public class PostgreSQLDialect extends Dialect {
 		functionFactory.arrayRemoveIndex_unnest( true );
 		functionFactory.arraySlice_operator();
 		functionFactory.arrayReplace();
+		functionFactory.arrayTrim_trim_array();
 
 		functionFactory.makeDateTimeTimestamp();
 		// Note that PostgreSQL doesn't support the OVER clause for ordered set-aggregate functions

hibernate-core/src/main/java/org/hibernate/dialect/function/CommonFunctionFactory.java

@@ -51,6 +51,7 @@ import org.hibernate.dialect.function.array.OracleArrayRemoveIndexFunction;
 import org.hibernate.dialect.function.array.OracleArrayReplaceFunction;
 import org.hibernate.dialect.function.array.OracleArraySetFunction;
 import org.hibernate.dialect.function.array.OracleArraySliceFunction;
+import org.hibernate.dialect.function.array.OracleArrayTrimFunction;
 import org.hibernate.dialect.function.array.PostgreSQLArrayConcatElementFunction;
 import org.hibernate.dialect.function.array.PostgreSQLArrayConcatFunction;
 import org.hibernate.dialect.function.array.PostgreSQLArrayPositionFunction;
@@ -3061,4 +3062,33 @@ public class CommonFunctionFactory {
 	public void arrayReplace_oracle() {
 		functionRegistry.register( "array_replace", new OracleArrayReplaceFunction() );
 	}
+
+	/**
+	 * H2, HSQLDB, CockroachDB and PostgreSQL array_trim() function
+	 */
+	public void arrayTrim_trim_array() {
+		functionRegistry.patternAggregateDescriptorBuilder( "array_trim", "trim_array(?1,?2)" )
+				.setArgumentsValidator(
+						StandardArgumentsValidators.composite(
+								new ArgumentTypesValidator( null, ANY, INTEGER ),
+								ArrayArgumentValidator.DEFAULT_INSTANCE
+						)
+				)
+				.setReturnTypeResolver( ArrayViaArgumentReturnTypeResolver.DEFAULT_INSTANCE )
+				.setArgumentTypeResolver(
+						StandardFunctionArgumentTypeResolvers.composite(
+								StandardFunctionArgumentTypeResolvers.invariant( ANY, INTEGER ),
+								StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE
+						)
+				)
+				.setArgumentListSignature( "(ARRAY array, INTEGER elementsToRemove)" )
+				.register();
+	}
+
+	/**
+	 * Oracle array_trim() function
+	 */
+	public void arrayTrim_oracle() {
+		functionRegistry.register( "array_trim", new OracleArrayTrimFunction() );
+	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayTrimFunction.java

@@ -0,0 +1,61 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
+ */
+package org.hibernate.dialect.function.array;
+
+import java.util.List;
+
+import org.hibernate.query.ReturnableType;
+import org.hibernate.query.sqm.function.AbstractSqmSelfRenderingFunctionDescriptor;
+import org.hibernate.query.sqm.produce.function.ArgumentTypesValidator;
+import org.hibernate.query.sqm.produce.function.StandardArgumentsValidators;
+import org.hibernate.query.sqm.produce.function.StandardFunctionArgumentTypeResolvers;
+import org.hibernate.sql.ast.SqlAstTranslator;
+import org.hibernate.sql.ast.spi.SqlAppender;
+import org.hibernate.sql.ast.tree.SqlAstNode;
+import org.hibernate.sql.ast.tree.expression.Expression;
+
+import static org.hibernate.query.sqm.produce.function.FunctionParameterType.ANY;
+import static org.hibernate.query.sqm.produce.function.FunctionParameterType.INTEGER;
+
+/**
+ * Oracle array_trim function.
+ */
+public class OracleArrayTrimFunction extends AbstractSqmSelfRenderingFunctionDescriptor {
+
+	public OracleArrayTrimFunction() {
+		super(
+				"array_trim",
+				StandardArgumentsValidators.composite(
+						new ArgumentTypesValidator( null, ANY, INTEGER ),
+						ArrayArgumentValidator.DEFAULT_INSTANCE
+				),
+				ArrayViaArgumentReturnTypeResolver.DEFAULT_INSTANCE,
+				StandardFunctionArgumentTypeResolvers.composite(
+						StandardFunctionArgumentTypeResolvers.invariant( ANY, INTEGER ),
+						StandardFunctionArgumentTypeResolvers.IMPLIED_RESULT_TYPE
+				)
+		);
+	}
+
+	@Override
+	public void render(
+			SqlAppender sqlAppender,
+			List<? extends SqlAstNode> sqlAstArguments,
+			ReturnableType<?> returnType,
+			SqlAstTranslator<?> walker) {
+		final String arrayTypeName = DdlTypeHelper.getTypeName(
+				( (Expression) sqlAstArguments.get( 0 ) ).getExpressionType(),
+				walker
+		);
+		sqlAppender.append( arrayTypeName );
+		sqlAppender.append( "_trim(" );
+		sqlAstArguments.get( 0 ).accept( walker );
+		sqlAppender.append( ',' );
+		sqlAstArguments.get( 1 ).accept( walker );
+		sqlAppender.append( ')' );
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayTrimTest.java

@@ -0,0 +1,99 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.orm.test.function.array;
+
+import java.sql.SQLException;
+import java.util.List;
+
+import org.hibernate.cfg.AvailableSettings;
+
+import org.hibernate.testing.orm.junit.DialectFeatureChecks;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.RequiresDialectFeature;
+import org.hibernate.testing.orm.junit.ServiceRegistry;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.hibernate.testing.orm.junit.Setting;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.PersistenceException;
+import jakarta.persistence.Tuple;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.fail;
+
+/**
+ * @author Christian Beikov
+ */
+@DomainModel(annotatedClasses = EntityWithArrays.class)
+@SessionFactory
+@RequiresDialectFeature( feature = DialectFeatureChecks.SupportsStructuralArrays.class)
+// Make sure this stuff runs on a dedicated connection pool,
+// otherwise we might run into ORA-21700: object does not exist or is marked for delete
+// because the JDBC connection or database session caches something that should have been invalidated
+@ServiceRegistry(settings = @Setting(name = AvailableSettings.CONNECTION_PROVIDER, value = ""))
+public class ArrayTrimTest {
+
+	@BeforeEach
+	public void prepareData(SessionFactoryScope scope) {
+		scope.inTransaction( em -> {
+			em.persist( new EntityWithArrays( 1L, new String[]{} ) );
+			em.persist( new EntityWithArrays( 2L, new String[]{ "abc", null, "def" } ) );
+			em.persist( new EntityWithArrays( 3L, null ) );
+		} );
+	}
+
+	@AfterEach
+	public void cleanup(SessionFactoryScope scope) {
+		scope.inTransaction( em -> {
+			em.createMutationQuery( "delete from EntityWithArrays" ).executeUpdate();
+		} );
+	}
+
+	@Test
+	public void testTrimOne(SessionFactoryScope scope) {
+		scope.inSession( em -> {
+			//tag::hql-array-trim-example[]
+			List<Tuple> results = em.createQuery( "select e.id, array_trim(e.theArray, 1) from EntityWithArrays e where e.id = 2", Tuple.class )
+					.getResultList();
+			//end::hql-array-trim-example[]
+			assertEquals( 1, results.size() );
+			assertEquals( 2L, results.get( 0 ).get( 0 ) );
+			assertArrayEquals( new String[] { "abc", null }, results.get( 0 ).get( 1, String[].class ) );
+		} );
+	}
+
+	@Test
+	public void testTrimAll(SessionFactoryScope scope) {
+		scope.inSession( em -> {
+			List<Tuple> results = em.createQuery( "select e.id, array_trim(e.theArray, 3) from EntityWithArrays e where e.id = 2", Tuple.class )
+					.getResultList();
+			assertEquals( 1, results.size() );
+			assertEquals( 2L, results.get( 0 ).get( 0 ) );
+			assertArrayEquals( new String[0], results.get( 0 ).get( 1, String[].class ) );
+		} );
+	}
+
+	@Test
+	public void testTrimOutOfRange(SessionFactoryScope scope) {
+		scope.inSession( em -> {
+			try {
+				em.createQuery( "select array_trim(e.theArray, 1) from EntityWithArrays e where e.id = 1" )
+						.getResultList();
+				fail( "Should fail because array is too small to trim!" );
+			}
+			catch (PersistenceException ex) {
+				assertInstanceOf( SQLException.class, ex.getCause() );
+			}
+		} );
+	}
+
+}